下面程序的运行结果是( )。 #include<iostream.h> class base{ protected: int a; public: base(){cout<<“0”;} }; Class base1:virtua1 base{ public: base1(){cout<<“1”;} }; class base2:virtual base{ public: base2(){cout<<“2”;} }; Class derived:public base1,public base2{ public: derived(){cout<<“3”;} }; void main() { derived obj; cout<<endl; }
A.0123
B.3120
C.0312
D.3012